This section provides background information related to the present disclosure which is not necessarily prior art.
An exhaust gas recirculation system for diesel engines is known from U.S. Pat. No. 5,671,600 A. Provided at the exhaust gas outlet or at the exhaust gas line respectively is a particle filter, to which an exhaust gas recirculation line is connected. The exhaust gas recirculation line opens upstream of a charge-air compressor in the inlet line. Provided inside the exhaust gas recirculation line is a valve for modifying the exhaust gas mass flow. The particle filter serves to protect the charge-air compressor or the charge-air cooler respectively against dirt contamination.
A particle filter in the main exhaust gas flow of a gasoline engine is known from DE 10 2012 021 882 A1. Unlike the diesel engine arrangement, the particle filter regenerates to the greatest possible extent without additional active measures, i.e. the particle mass which has been retained up to that point (soot particles with attached or embedded hydrocarbons) combusts under normal gasoline engine peripheral conditions, essentially to form CO2 or H2O respectively. For this purpose, sufficiently high exhaust gas temperatures of more than 500° C. as well as oxygen are required, for combustion. This exhaust gas temperature is attained soon after the start of the engine, in the most widely differing operating ranges of the gasoline engine. Since the majority of gasoline engines are stoichiometrically operated, the oxygen content in the exhaust gas may be too low for a complete combustion of the particle mass contained in the filter. In this situation, conventional deceleration fuel cut-off phases of the gasoline engine are of assistance, in which, due to the absence of the load requirement from the driver, the engine injection is switched off for reasons of fuel consumption. Since the engine, with a gear engaged as an engine brake, results in the reduction of the vehicle's speed, clean air is flushed through the exhaust system by the slow-combusting engine. This non-combusted air impacts on the particles in the particle filter, heated previously by the engine exhaust gas. When an adequate temperature is reached, these particles catch fire and combust to form gases which can escape through the particle filter, cleaning the particle filter as a result.
Additional measures, such as a secondary air system, in order to achieve the active regeneration of the particle filter by an air surplus, are known from DE 10 2013 003 701 A1, DE 10 2013 008 426 and WO 2008 127 755 A2.
DE 10 2009 014 277 A1 describes a device for the operation of a diesel engine having an exhaust gas line and an exhaust gas recirculation line, which connects to an inlet line. The exhaust gas recirculation line can optionally be connected to the exhaust gas system in a regeneration mode of the diesel particle filter located in the exhaust gas recirculation line by means of a three-way valve, wherein, during regular operation, the exhaust gas recirculation line is in flow connection with the inlet line by way of said three-way valve for the purpose of exhaust gas return.
DE 10 2010 046 747 A1 describes a method for the operation of a gasoline engine having a three-way catalytic converter and downstream particle filter. For the purpose of regeneration of the particle filter located in the exhaust gas line, a bypass is provided, which is routed past the three-way catalytic converter, wherein an air pump for the supply of secondary air is provided inside this bypass for the purpose of the regeneration of the particle filter. At the same time, in this case, a low-pressure exhaust gas recirculation line is supplied with secondary air.
EP 2 194 351 B1 describes an exhaust gas cooler for a diesel engine.